Some growers claim that Paphiopedilum sanderianum isn't that difficult to grow, but the relative dearth of cultivated plants at shows as well as private collections seems to indicate otherwise. I have seen many offerings of seedlings but I rarely see flowering plants. Some of the best known cultivars languish even now in the hands of some of the most respected of Paph growers.
Especially for the more difficult orchid species, plants are best grown under conditions approximating those the plants would normally encounter in the wild. The conditions I refer to are all-inclusive and include such factors as temperature, humidity and position (with respect to the sun as well as to air flow), and the composition of the substrate as well. Some species are more tolerant of variability of conditions than others, and species of very limited distribution both geographically and climatically can be very intolerant to changes.
It is my understanding that P. sanderianum can be very finicky in some respects. First blooming seedlings often die shortly after flowering. I have been told that the first spike should be removed shortly after the last flower has opened, to conserve energy for new growth.
I won't specify cultural requirements here, as any good book on Paphs should provide all the information needed for the cultivation of sanderianum. As any comprehensive reference will indicate, its native climate is relatively stable throughout the year, varying mostly in rainfall totals (ranging from moderate in 'dry' months to monsoonal in the 'wet' season) and prevailing wind direction. Temperatures remain the same throughout the year, with average highs of around 83 degrees F and lows around 70 degrees, indicating a fairly tight diurnal range. While growers can usually meet the watering requirements, the temperature requirements can be expensive to maintain. Keeping any greenhouse (or even a home) in a northern climate within the proper range can require a considerable amount of energy for heating as well as cooling.
As is true for many species orchids, Paph sanderianum can also be intolerant of root disruption, and repotting should be minimized in frequency. For the same reason don't divide your plant unless it falls apart of it's own volition, which in itself may be a really bad sign in a young (less than 15-20 years) plant. Similarly, be very careful in purchasing divisions of sanderianum, being aware that you are acquiring a plant that may well be recovering from a relatively massive trauma.
Assume that this plant reqires consistency above all else. Consistancy can be maintained by choosing its proper location in the growing area and leaving it there permanently. Resist the urge to move or rotate the plant to achieve better or faster growth. If you have to move the plant for any reason, mark its orientation on the shelf so you can replace it in the same position.
Stability. That's the key, and it's not so easy to achieve.